1. Field of the Invention
The present invention relates to a process for purifying Tylosin by selective adsorption on polymeric resins. 2. Description of the Background
As reported in both the scientific and patent literature, Tylosin base is usually extracted from the fermentation broth previously brought to a pH of 8.5 by chlorinated organic solvents, such as dichloromethane or chloroform or nonchlorinated solvents such as methyl-isobutylketone.
The combined organic extracts are then concentrated in vacuo and, after decoloration with activated carbon, Tylosin base precipitates by addition of n-hexane.
Alternatively, Tylosin base can be transferred from the organic extract into an aqueous phase in the form of a soluble salt by neutralization with a suitable organic or inorganic acid (tartaric or phosphoric acid). The aqueous solution containing the soluble salts of Tylosin is successively dried in vacuo (spray-drier) to obtain the antibiotic in the form of salt of the acid used.
According to the methods above described, it is not possible to reach a complete elimination of the impurities present, in same cases, in particularly high amounts in the fermentation broth, so that the quality of the final product depending on the type of these impurities (colors or fermentation by-products) is often unsatisfactory both in the titer and in the analytical and organoleptic properties.
The invention eliminates the above mentioned inconveniences and discloses a new method for purifying Tylosin which is very simple and allows one to obtain a product having the specifications in accordance with the requirements.